Prediction method of shale adsorption capacity based on adsorption characteristic curve and characteristic equation

A characteristic curve and characteristic equation technology, applied in the field of prediction of shale adsorption capacity, can solve problems such as difficult methane adsorption capacity and uniform surface assumption conditions are difficult to meet, and achieve the effect of wide application value

Inactive Publication Date: 2020-06-26
CHINA UNIV OF GEOSCIENCES (WUHAN)
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  • Description
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Problems solved by technology

The pore surface available for adsorption in shale is highly heterogeneous, and the uniform surface assumption required by the Langmuir model is difficult to satisfy
In addition, both the Langmuir model and the SDR model are isothermal adsorption models, and the fitting parameters are temperature-dependent. The methane adsorption cannot be directly expressed as a function of temperature and pressure, and it is difficult to efficiently calculate the methane adsorption of reservoirs in different regions.

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  • Prediction method of shale adsorption capacity based on adsorption characteristic curve and characteristic equation
  • Prediction method of shale adsorption capacity based on adsorption characteristic curve and characteristic equation
  • Prediction method of shale adsorption capacity based on adsorption characteristic curve and characteristic equation

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Embodiment 1

[0060] Please refer to figure 1 , the embodiment of the present invention provides a method for predicting the amount of shale adsorption based on the adsorption characteristic curve and the characteristic equation, including the following steps:

[0061] S1. Collect organic shale samples, and vacuumize the organic shale samples after treatment; the processed organic shale samples are particles with a particle size of 60-80 mesh.

[0062] S2. Using methane (CH 4 ) as an adsorbate, under high temperature and high pressure vacuum conditions, carry out isothermal adsorption on the organic shale sample with dry samples and equilibrium water samples at multiple temperatures, and collect adsorption data.

[0063] S3. Using the supercritical state DA equation to fit the methane isothermal adsorption data, obtain the maximum adsorption capacity, characteristic adsorption energy, parameters k, n, and calculate the adsorption potential and excess adsorption capacity;

[0064] Specific...

Embodiment 2

[0096] Using the fitting method of the adsorption characteristic curve and the characteristic equation of Example 1 of the present invention, Wufeng Formation shale (JYW-1) and Niutitang Formation shale (CYN-1) in the marine organic shale reservoir in South my country Fitting adsorption characteristic curve and characteristic equation of downhole shale samples.

[0097] (1) Collect the data of methane isothermal adsorption, and substitute relevant data in formula (3) to obtain the maximum adsorption capacity, characteristic adsorption energy, parameters k and n of the two groups of samples respectively, as shown in Table 1;

[0098] Table 1 Fitting data of supercritical DA model for two groups of shale samples

[0099]

[0100] (2) According to the fitting parameters, the adsorption potential, excess adsorption capacity and absolute adsorption capacity were calculated according to the formulas (2), (3) and (4). figure 2 , image 3 , Figure 4 , Figure 5 ;

[0101] (3)...

Embodiment 3

[0105] According to the relationship between the adsorption amount and temperature and pressure in the characteristic equation, the temperature and pressure conditions of the reservoir can be substituted into the equation to calculate the theoretical value of the adsorbed gas content of the reservoir; Experiments show that the maximum adsorption capacity of Wufeng shale will decrease by 14.02%, while that of Niutitang shale will decrease by 42.38%. The shale in Titang Formation contains 44.27%-46.63% nitrogen, which will reduce the maximum adsorption capacity of shale by about 30%. Based on this, the actual value of methane adsorption capacity in different reservoirs in geological environment can be calculated, as shown in Table 3;

[0106] Table 3 Prediction of adsorbed gas content of two groups of shale reservoirs

[0107]

[0108] It can be seen from Table 3 that the Wufeng Formation shale has a larger methane adsorption capacity than the Niutitang Formation shale, and t...

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Abstract

The invention discloses a shale adsorption capacity prediction method based on an adsorption characteristic curve and a characteristic equation. The method comprises the steps of collecting an organicmatter shale sample for vacuumizing; collecting isothermal adsorption data of methane; calculating an adsorption potential and an excessive adsorption capacity; correcting the excessive adsorption capacity into an absolute adsorption capacity; performing nonlinear fitting on the absolute adsorption capacity and the adsorption potential to obtain an initial adsorption characteristic curve; obtaining an optimal fitting curve as an optimal adsorption characteristic curve, taking a fitting equation corresponding to the optimal adsorption characteristic curve as the characteristic equation, and rewriting the characteristic equation into a function of adsorption capacity and temperature and pressure by use of an adsorption potential theory; and acquiring the temperature and pressure of a reservoir stratum and related geological data, importing the temperature and pressure of the reservoir stratum and the related geological data into the function of adsorption capacity and temperature and pressure, and obtaining the organic matter shale adsorption capacity in the reservoir stratum through calculation. According to the shale adsorption capacity prediction method based on the adsorption characteristic curve and the characteristic equation, a model can further predict the adsorption gas content of the organic matter shale reservoir stratum, and the method has broad application value indetailed description of the gas content of the reservoir stratum.

Description

technical field [0001] The invention relates to the technical field of unconventional oil and gas exploration and development, in particular to a method for predicting shale adsorption capacity based on adsorption characteristic curves and characteristic equations. Background technique [0002] Methane high-temperature and high-pressure isothermal adsorption experiment is an effective means to obtain the adsorption capacity of organic matter shale. Usually, multiple sets of isothermal adsorption data can be obtained according to the experimental requirements. At present, the Langmuir model is the most common adsorption data fitting model. In addition, the SDR model also has a better fitting effect. During the fitting process, both models need to correct the excess adsorption to absolute adsorption. [0003] Since the temperature and pressure conditions of underground reservoirs belong to the supercritical environment of high temperature and high pressure, it is particularly...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G06F30/20G06F17/11
CPCG06F17/11G06F30/20
Inventor 戴方尧胡海燕
Owner CHINA UNIV OF GEOSCIENCES (WUHAN)
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